Trek Bottom Bracket Bearing Guide by Enduro. This reversible bearing guide has one side for 24mm ID bearings and the other side for 22mm ID bearings. The 24mm side is used for all Shimano bearings and for the drive side bearing of SRAM GXP cranks. The 22mm side is for pressing in the non-drive side SRAM GXP bearing. Can be used with any bearing press that utilizes an 8mm OD threaded rod.